1. Field of the Invention
The present invention relates to a living body observation device for using a color image signal obtained by picking up an image of a living body to display the image as a spectral image on a display device by signal processing.
2. Description of the Related Art
Conventionally, an endoscope device for obtaining an endoscope image in a body cavity by radiating illumination light is widely used as a living body observation device. This kind of endoscope device uses an electronic endoscope including an image pickup unit for guiding illumination light from a light source into a body cavity using a light guide and picking up an image of a shooting object by optical feedback of the light. Such device processes an image pickup signal from the image pickup unit by a video processor to display an endoscope image on an observation monitor and observe an observed part such as a diseased part.
As one scheme in performing normal observation of living tissue by an endoscope device, a light source emits white light in a visible light region, and irradiates an shooting object with frame sequential light via an RGB rotating filter, for example, and a video processor synchronizes optical feedback of the frame sequential light and processes an image to obtain a color image. As another scheme in performing normal observation of living tissue by the endoscope device, color chips are arranged on a front surface of an image pickup surface of the image pickup unit of the endoscope, the light source emits white light in a visible light region and the color chips separate optical feedback of the white light into respective color components to pick up an image, and the video processor processes an image to obtain a color image.
Living tissue has different light absorption characteristics and scattering characteristics depending on wavelengths of radiated light. As such, Japanese Patent Application Laid-Open Publication No. 2002-95635, for example, discloses a narrowband-light endoscope device for irradiating living tissue with illumination light in a visible light region as narrowband RGB frame sequential light with discrete spectral characteristics and obtaining tissue information of a desired deep part of the living tissue.
Japanese Patent Application Laid-Open Publication No. 2003-93336 discloses a narrowband-light endoscope device for processing an image signal with illumination light in a visible light region, generating a discrete spectral image, and obtaining tissue information of a desired deep part of living tissue.
In the device according to Japanese Patent Application Laid-Open Publication No. 2003-93336, a light quantity control unit performs processing to decrease illumination light quantity to obtain a spectral image (for example, illumination light radiation timing control, light chopper control, lamp application current control or electronic shutter control) for the illumination light quantity to obtain a normal light observation image, and controls to avoid saturation of a CCD being an image pickup unit.